A head mounted display (HMD) is worn on a user's head for displaying an image. Generally, HMDs are configured as helmets or goggles, depending on how the display is to be worn. A HMD is a personal see-through device designed to view still or video images or data that nonetheless permits the user to view his surroundings.
The critical component of any HMD is the optical display system. Currently existing technologies, such as retinal direct projection, typically make use of expensive optics and mirrors and require high-resolution displays and expensive control circuitry.